When you replace a timing belt or otherwise have to check timing, here's the procedure for a 924:

1) Turn the crank with a socket until the forward most (#1) cylinder is at top dead center with both valves closed - the nic on the engine pulley should be aligned with the pointer.

2) The indented dot on the back of the camshaft pulley has a dot which should be aligned with the nearby marker. (There is also an indented dot on the front which is not the right for timing.)

3) Place the belt around of the engine pulley without moving the pulley. Bring the right side of the belt over the camshaft pulley and work the cogs into the pulley. Bring the belt around the tensioner side and snug down the tensioner. Check crank/cam alignment and adjust the tension on the belt to allow less than 1/8 lateral movement on the long side of the belt.

4) Finally, with crank and cam aligned, loosen the distributor collar and adjust the distributor so that the rotor is aligned to the contact that fires the #1 cylinder. This should get the engine started and you might tweek the distributor for fine tuning. We used to call this "dry timing" when working on motorcycles.

Hi, I have a very newbie type question for you and I really hope you can give me the answer. In your step number 2, which side of the cam pulley is the back that faces the engine ? One side of mine has the VW and Audi logos and Made in England. The other side is completely blank. Which side of this pulley faces the engine ?
Thank you very, very much for a reply.

Respectfully,
Jim.

pmcaya2 wrote:

When you replace a timing belt or otherwise have to check timing, here's the procedure for a 924:

1) Turn the crank with a socket until the forward most (#1) cylinder is at top dead center with both valves closed - the nic on the engine pulley should be aligned with the pointer.

2) The indented dot on the back of the camshaft pulley has a dot which should be aligned with the nearby marker. (There is also an indented dot on the front which is not the right for timing.)

3) Place the belt around of the engine pulley without moving the pulley. Bring the right side of the belt over the camshaft pulley and work the cogs into the pulley. Bring the belt around the tensioner side and snug down the tensioner. Check crank/cam alignment and adjust the tension on the belt to allow less than 1/8 lateral movement on the long side of the belt.

4) Finally, with crank and cam aligned, loosen the distributor collar and adjust the distributor so that the rotor is aligned to the contact that fires the #1 cylinder. This should get the engine started and you might tweek the distributor for fine tuning. We used to call this "dry timing" when working on motorcycles.

Where in Canada might you be? There are surely Canadian experts who might be around who can help you.

That said I too have a 1980 931 and if you rotate the cam shaft there is a dot on the back side of it closest to the pointer on the valve cover. If this isn't clear enough for you the back side is the flat face closest to the drivers seat and the front face is closest to the front bumper.

Hi everyone I have been having trouble getting the car started and I have now replaced pretty much the whole fuel system as I found many problems with it. I have just found that the dot on the cam pulley is on the front not the back so i'm guessing the timing has been messed with. I had a look through haynes and cant find a decent description of setting the crank to tdc.

Does anyone have a pic of the mark on the bottom pulley and is there a reference mark on the flywheel to check against?

Thanks_________________It could always be worse so don't worry about it and get the spanners out

Ok cool. You would have thought the haynes would have that little nugget of info. Thanks for that I will get that sorted tomorrow._________________It could always be worse so don't worry about it and get the spanners out

...to begin with...
...the crankshaft, pistons, and rods are all hooked together and will always be in the same relationship to each other....two pistons up and two pistons down (180 apart) (always)....
...the camshaft is not hooked to the crankshaft with anything but the timing belt...the cam has lobes on it that push the valves open...thusly, you do not want the valves in a cylinder to be open when the piston is up...or...CRASH!...bent valves, and possible piston damage...DON'T FORCE ANYTHING!...this can happen with just the use of the starter on an improperly timed engine...
...that said, there is only one position of the cam pulley in relation to the crankshaft pulley where the car is going to run right...
...the proper orientation of the cam pulley is with the deep side toward the engine...
...hopefully, when you begin the procedure, the cam is set correctly for the engine being at top center...top center is established by rotating the engine (24mm socket on the center bolt of the crank pulley) until you see a fine line on the flywheel marked Z-1...I set this line at the bottom edge of the little window in the bell housing...(EVERY TIME Z-1 is there, #1 piston will be at top center)
...remember...if you should feel solid resistance when rotating the engine to top center.....STOP!...you probably need to move the cam, as valves may be touching a piston somewhere...DON"T FORCE ANYTHING!...
...when you see Z-1...stop!...the crank is now set to top center...now look at the front of the engine at the crank pulley...you should see a small chisel mark adjacent to a molded-in timing pointer on the engine front...this makes installation of the belt easier....as you can see top center as you work...
...on the cam pulley backside, you will see a "notch" (larger among a row of notches)...align this notch with the pointer on the top front of the valve cover...the engine is now in time...now, thread the timing belt over the crank pulley, to the inside of the tensioner, and over the cam pulley without allowing either the cam or engine pulley to change location....as you do this, make sure the tension on the long side of the belt is as tight as you can pull it while threading the belt...tension the tensioner to spec and lock the bolt at 27ft lbs.
...now check if Z-1 is still there...if so, rotate the engine at least two(2) full turns and see if the marks still line up...if not, do it again until they do (hint: as you tighten the tensioner, it will have a tendency to slightly move the crankshaft in a counterclockwise (as you face the engine) direction...if ever in doubt when checking for #1 piston top center and timing, take the oil cap off and look at the first two cam lobes... the intake (first lobe) should point to the 9 o'clock position while the exhaust lobe (second lobe) should point to the 2 o'clock position (this will never change, and is the proper relationship between the #1 piston at top center and the valves for #1) and I use it as a constant when setting the cam...the distributor may now be inserted and timed to the rest of the engine...be sure to use Z-1 in all initial timing settings...

Coldwarvet description is well done and more detailed than my previous post. I would add my step 4. after you get cam and crank aligned:

4) Finally, with crank and cam aligned, loosen the distributor collar and adjust the distributor so that the rotor is aligned to the contact that fires the #1 cylinder. This should get the engine started and you might tweek the distributor for fine tuning. We used to call this "dry timing" when working on motorcycles.

...my post is directed at establishing initial engine timing only , and assumes the distributor isn't even in the engine yet (a lot of these cars are purchased this way unfortunately)...isolating procedures helps to prevent things from getting too wordy and complicated...I well understand that there are many here that, by the time they discover this site, are so frustrated that they are either neglecting the basics or were never aware of what they were to begin with...and that's OK, as I see this site as a place to go to keep these cars running without feeling intimidated...
...I have seen so much written about cam timing here, which is really pretty simple, but leaves me with the impression that there must be a number of different cam drive wheels out there........or not...